Am I a bad mom??

My daughter is a month old/40weeks(she was born 5weeks ealry only spent 2weeks in the nicu has been home for 3weeks) on the 31st I called my sister(she’s 16) and talk to her about watching my 16month old son and my daughter and she was all for it she had been asking all week if she could have them for a day, I told her that I had errands to run on the 1st and didn’t know when I would be done because my Hubbys aunt had her baby on the 31st and wanted us to come see her at the hospital and then I had to go to the insurance and dmv office. The 1st comes and I call my sister to let her know we were on our way to drop off the kids and my mom tells me that their not home and I would have to wait till she was done with her running around(I never asked my mom to babysit) and I asked her why and told her that my sister said the kids could come over just leave my sister home so I need up not dropping the kids off till 12pm , I called my sister when I was done at the hospital to see if she wanted me to come pick up the kids that was around 230 she asked if she could keep them a little longer so I asked her if it was okay if I went home and took a nap considering my daughter has been up all night for 2nights in a row by then and I hadn’t had any sleep I was exhausted she said that she was okay and to get sleep I went home and took a little nap before my hubbys appointment at the dmv at 330 we didn’t get out of the dmv office till 520. I then called my sister again she said my son was sleeping and my daughter was laying with her and told me just to wait till my son was awake so my hubby and I went to his friends house till 6. I got to my sister(my moms house at 606 because my hubbys friend lives 4mins from them. Well when I got their my sister said she didn’t mind and was happy that she got them and told me that she wanted them again sometime before next week, we were talking and I told her that my mom told me that because my kids where at my house she couldn’t do what she wanted to do with her step kids then my sister told me that my mom asked when I was gonna pick up my kids but was posting on Facebook about how happy she was to have them at her house but she wasn’t watching them so I don’t know what her deal was. I asked my mom why she had a big deal about them at her house and she told me because what mom leaves their 1month old for 5hours and that she thought they ran out of breast milk (for the baby who only eats 1.25oz every 3hrs and I sent 6oz over) and then she said she started thinking how I was pry tired and needed a break and she pry should have been more understanding. I told her what happens when I go back to work and my kids have to be without me longer. My mom always had my grandparents from her first kid at 15 up until we were placed into different homes and she wasn’t around for 4yrs. But am I a bad mom?? Was it okay that I left my month old for that long I know she was safe she had diapers wipes and milk. Do you leave your kids for a few hours?? With my son my hubby and I were both getting out of foster/adoption homes and recounting with our family’s so we didn’t leave him with them until he was 7months old when my hubby and I had a self care day.